The invention relates to a method for packet switched transmission of data packets containing useful information and sorted into a first sequence in a cellular radio communication system.
The invention further relates to a radio communication system for packet switched transmission of data packets containing useful information and sorted into a first sequence.
Radio communication systems are increasingly gaining significance both in the business sector and among consumers. In radio communication systems, information such as speech, pictures or other data is transmitted between a base station and a subscriber station, in particular a mobile station, over a radio interface with the aid of electromagnetic waves. The electromagnetic waves are emitted on carrier frequencies that lie within the intended frequency band for the system concerned. For future mobile radio systems the radio interface is sub-divided into transmission channels according to the TD/CDMA transmission method or the FD/CDMA transmission method so that the the channels separate the radio resources of the radio interface between the individual subscriber stations. For UMTS (universal mobile telecommunication system) or other third generation systems, the frequencies planned for the transmission channels are typically in the frequency band of around 2000 MHz.
For the above-mentioned UMTS radio communication system there is a distinction between modes known as the FDD mode (frequency division duplex) and the TDD mode (time division duplex). The TDD mode is distinguished in particular by the fact that a common frequency band is used for data transmission in both the upward direction (UL uplink) and the downward direction (DL downlink), whereas the FDD mode uses a different frequency band for each of the two transmission directions.
In order to transmit data between a base station and a subscriber station it is possible to use on the one hand methods based on connection-oriented concepts, and on the other hand methods based on logical connections. In the case of connection-oriented data transmission, physical resources of the radio interface must be made available throughout the entire data transmission time. In the case of data transmission via logical connections, there is no need for physical resources to be permanently provided.
An example of data transmission via logical connections is data transmission by data packets. In this case a logical connection exists between the base station and the subscriber station throughout the duration of the entire transmission, but physical resources are provided only during the actual transmission times of the data packets. This method is based on the fact that the data is transmitted in short data packets, between which quite long pauses can occur. In the pauses between the data packets, the physical resources are available for other logical connections. Physical resources are saved compared to a logical connection.